1. Field of the Invention
This invention relates to an ultrasound diagnostic apparatus which can operate in any one of different modes including a Doppler-based mode using steerable continuous wave (SCW).
2. Description of the Related Art
U.S. Pat. No. 5,555,534 corresponding to PCT application WO96/04588 discloses an ultrasonic receive system including first and second separate receive beamformers. The first receive beamformer is optimized for imaging modes such as B-mode and color Doppler flow imaging, and therefore has high spatial resolution and wide bandwidth. The second receive beamformer has a wide dynamic range and is dedicated for use in acquiring spectral Doppler information, which is typically narrowband compared to imaging information. The second receive beamformer achieves the sensitivity and low-noise performance of a dedicated single-channel pencil probe instrument. The second receive beamformer also performs electronic beam steering. Both the first and second receive beamformers can operate through a common transducer array, thereby increasing exam efficiency and permitting registration of spectral Doppler information with a B-mode or color Doppler flow image.
The ultrasonic receive system in U.S. Pat. No. 5,555,534 can operate in any one of the B-mode, the color Doppler mode, the beam-steering Doppler mode. During the B-mode or the color Doppler mode of operation, the first receive beamformer is used. During the beam-steering Doppler mode of operation, the second receive beamformer is used. The ultrasonic receive system in U.S. Pat. No. 5,555,534 has a complicated structure since the first and second receive beamformers are separate from each other.
It is an object of this invention to provide a simple ultrasound diagnostic apparatus.
A first aspect of this invention provides an ultrasound diagnostic apparatus comprising a probe outputting RF signals; N phase detectors for converting the RF signals outputted from the probe into baseband signals In and Qn, where xe2x80x9cNxe2x80x9d denotes a first predetermined natural number and xe2x80x9cnxe2x80x9d denotes a second predetermined natural number set as 2xe2x89xa6nxe2x89xa6N; and a reception beam former for processing the baseband signals In and Qn into a time-division-multiplexed signal; wherein the reception beam former comprises means for multiplying the baseband signals In and Qn by phase shift data to generate multiplication-resultant signals, means for delaying the multiplication-resultant signals to generate delay-resultant signals; and means for combining the delay-resultant signals into the time-division-multiplexed signal.
A second aspect of this invention is based on the first aspect thereof, and provides an ultrasound diagnostic apparatus further comprising means for selecting either a set of the RF signals or a set of the baseband signals In and Qn, and feeding the selected signal set to the reception beam former.
A third aspect of this invention is based on the second aspect thereof, and provides an ultrasound diagnostic apparatus wherein the multiplying means in the reception beam former comprises multipliers for multiplying the baseband signals In and Qn by the phase shift data, and the multipliers are operative for multiplying the RF signals by weighting factors when the set of the RF signals is fed to the reception beam former.
A fourth aspect of this invention is based on the first aspect thereof, and provides an ultrasound diagnostic apparatus further comprising a demodulation phase detector for subjecting the time-division-multiplexed signal to a demodulation process.
A fifth aspect of this invention is based on the fourth aspect thereof, and provides an ultrasound diagnostic apparatus wherein the demodulation phase detector comprises means for demultiplexing the time-division-multiplexed signal.
A sixth aspect of this invention is based on the first aspect thereof, and provides an ultrasound diagnostic apparatus wherein the delaying means comprises means for delaying the multiplication-resultant signals by fixed time intervals.
A seventh aspect of this invention provides an ultrasound diagnostic apparatus comprising a first transducer element (P1) outputting a first RF signal; a second transducer element (P2) outputting a second RF signal; a third transducer element (P3) outputting a third RF signal; first means (12) for demodulating the third RF signal into a baseband in-phase signal and a baseband quadrature signal; a first multiplier (M5); a second multiplier (M6); an adder (A1) connected to the first and second multipliers (M5, M6) for adding an output signal from the first multiplier (M5) and an output signal from the second multiplier (M6); second means (SW1, SW2) for selecting either a set of the first and second RF signals or a set of the baseband in-phase and quadrature signals, for feeding the first and second RF signals to the first and second multipliers (M5, M6) respectively when the set of the first and second RF signals is selected, and for feeding the baseband in-phase and quadrature signals to the first and second multipliers (M5, M6) respectively when the set of the baseband in-phase and quadrature signals is selected; third means (W1, W2) for feeding first and second weighting factors to the first and second multipliers (M5, M6) respectively when the second means (SW1, SW2) selects the set of the first and second RF signals; and fourth means (5) for feeding first and second phase shift signals to the first and second multipliers (M5, M6) respectively when the second means (SW1, SW2) selects the set of the baseband in-phase and quadrature signals; wherein the first multiplier (M5) multiplies the first RF signal and the first weighting factor and the second multiplier (M6) multiplies the second RF signal and the second weighting factor when the second means (SW1, SW2) selects the set of the first and second RF signals; and wherein the first multiplier (M5) multiplies the baseband in-phase signal and the first phase shift signal and the second multiplier (M6) multiplies the baseband quadrature signal and the second phase shift signal when the second means (SW1, SW2) selects the set of the baseband in-phase and quadrature signals.
An eighth aspect of this invention is based on the seventh aspect thereof, and provides an ultrasound diagnostic apparatus further comprising fifth means (6, 7) for demodulating an output signal from the adder (A1) into a demodulation-resultant in-phase signal and a demodulation-resultant quadrature signal when the second means (SW1, SW2) selects the set of the first and second RF signals, and for demultiplexing the output signal from the adder (A1) into a demultiplexing-resultant in-phase signal and a demultiplexing-resultant quadrature signal when the second means (SW1, SW2) selects the set of the baseband in-phase and quadrature signals.
A ninth aspect of this invention is based on the eighth aspect thereof, and provides an ultrasound diagnostic apparatus wherein the fifth means (6, 7) comprises a multiplier generator (7) for generating first and second multiplier signals; a third multiplier (M9) for multiplying the output signal from the adder (A1) and the first multiplier signal, wherein an output signal of the third multiplier (M9) is the demodulation-resultant in-phase signal when the second means (SW1, SW2) selects the set of the first and second RF signals, and the output signal of the third multiplier (M9) is the demultiplexing-resultant in-phase signal when the second means (SW1, SW2) selects the set of the baseband in-phase and quadrature signals; and a fourth multiplier (M10) for multiplying the output signal from the adder (A1) and the second multiplier signal, wherein an output signal of the fourth multiplier (M10) is the demodulation-resultant quadrature signal when the second means (SW1, SW2) selects the set of the first and second RF signals, and the output signal of the fourth multiplier (M10) is the demultiplexing-resultant quadrature signal when the second means (SW1, SW2) selects the set of the baseband in-phase and quadrature signals.